Mixed signal synthesis behavioral models and use in circuit design optimization

Abstract

A method and apparatus for the synthesis of electronic circuits is described herein. More particularly, the system supports the synthesis of both analog-only, and mixed digital/analog circuitry. The circuit designers knowledge is reused to effect the simulation of mixed analog and digital circuitry, determining data points and curve-fitting the data points to determine a model that closely approximates the simulated circuit performance. The model describes the parameterization of circuit features with respect to circuit performance. The parameterization is used to develop a behavioral model of the circuit that does not retain any of the physical description of the circuit.

What is claimed is:  
     
       1. A method of synthesizing an electronic circuit, comprising the steps of: 
       developing a behavioral model of a circuit cell which describes the behavior of the circuit cell, said step of developing a behavioral model includes determining the behavior of the circuit cell as a function of information about said circuit cell's physical description and design parameters, determining a set of design parameters that affect the cell's behavior, optimizing the performance characteristics of said electronic circuit to best match said set of design parameters, and creating a behavioral model that relates the behavior of said circuit cell to said design parameters;  
       associating said behavioral model with the physical description of a circuit cell;  
       storing the behavioral model together with the associated circuit cell physical description in a synthesis library as a cell model and definition, together with performance specifications and design parameters;  
       creating a synthesis plan for the creation of a particular type of circuit that includes a number of said cell models and definitions, performance specifications, and design parameters;  
       retrieving said synthesis plan in order to create a new circuit design of similar type with different performance specification requirements;  
       selecting those circuit cell models and definitions specified by the synthesis plan, and whose performance specification requirements matches the performance specification requirements of a circuit cell of the new circuit; and,  
       synthesizing the new electronic circuit by incorporating the physical description and design parameters associated with the selected circuit cell models and definitions into said new circuit design.  
     
     
       2. The method of  claim 1  wherein the behavioral model comprises a polynomial expression that relates the design parameters of a circuit cell to the behavior of said circuit cell. 
     
     
       3. The method of  claim 1  wherein the behavioral model comprises a table having a plurality of entries wherein each of said entries relates a set of values of design parameters of a circuit cell to the behavior of said circuit cell. 
     
     
       4. The method of  claim 3  wherein the entries in said table are interpolated to determine design parameter values and circuit cell associated behaviors not explicitly stored in said table. 
     
     
       5. The method of  claim 1  wherein said chosen design parameters are chosen automatically by a system operating the method. 
     
     
       6. The method of  claim 1  wherein said chosen design parameters are chosen by an operator of the method. 
     
     
       7. The method of  claim 1  wherein said step of developing comprises: 
       determining a set of design parameters which most affect the behavior of the circuit cell; and,  
       associating thereafter said set of design parameters with said model.  
     
     
       8. The method of  claim 1  wherein said circuit is simulated using a SPICE simulator. 
     
     
       9. The method of  claim 1  wherein said set of chosen design parameters includes any of minimal, maximal, or optimal value of any of said design parameters. 
     
     
       10. The method of  claim 1  wherein said physical description of said circuit cell comprises the topology of said circuit cell. 
     
     
       11. The method of  claim 1  wherein said physical description of said circuit cell comprises a list of components in said circuit cell. 
     
     
       12. A system for synthesizing electronic circuits, comprising 
       a computer processing storage unit with media storage;  
       a modeler that allows the system or a user to perform the steps of  
       developing a behavioral model of a circuit cell which describes the behavior of the circuit cell, said step of developing a behavioral model includes determining the behavior of the circuit cell as a function of information about said circuit cell's physical description and design parameters, determining a set of design parameters that most affect the cell's behavior, optimizing the performance characteristics of said electronic circuit to best match said set of design parameters, and creating a behavioral model that relates the behavior of said circuit cell to said design parameters,  
       associating said behavioral model with the physical description of a circuit cell,  
       storing the behavioral model together with the associated circuit cell physical description in a synthesis library as a cell model and definition, together with performance specifications and design parameters, and,  
       creating a synthesis plan for the creation of a particular type of circuit that includes a number of said cell models and definitions, performance specifications, and design parameters;  
       an input device to allow input of a desired circuit cell behavior in an electronic circuit; and,  
       a synthesizer that allows the system or a user to perform the steps of  
       retrieving said synthesis plan in order to create a new circuit design of similar type with different performance specification requirements,  
       selecting those circuit cell models and definitions specified by the synthesis plan, and whose performance specification requirements matches the performance specification requirements of a circuit cell of the new circuit, and,  
       synthesizing the new electronic circuit by incorporating the physical description and design parameters associated with the selected circuit cell models and definitions into said new circuit design.  
     
     
       13. A computer readable medium having computer instructions thereon that when loaded into a computer causes the computer to perform the steps of: 
       allowing a user to develop a behavioral model of a circuit cell which describes the behavior of the circuit cell, said step of developing a behavioral model includes determining the behavior of the circuit cell as a function of information about said circuit cell's physical description and design parameters, determining a set of design parameters that most affect the cell's behavior, optimizing the performance characteristics of said electronic circuit to best match said set of design parameters, and creating a behavioral model that relates the behavior of said circuit cell to said design parameters;  
       associating said behavioral model with the physical description of a circuit cell;  
       storing the behavioral model together with the associated circuit cell physical description in a synthesis library as a cell model and definition, together with performance specifications and design parameters;  
       creating a synthesis plan for the creation of a particular type of circuit that includes a number of said cell models and definitions, performance specifications, and design parameters;  
       allowing a user to retrieve said synthesis plan in order to create a new circuit design of similar type with different performance specification requirements;  
       selecting those circuit cell models and definitions specified by the synthesis plan, and whose performance specification requirements matches the performance specification requirements of a circuit cell of the new circuit; and,  
       synthesizing the new electronic circuit by incorporating the physical description and design parameters associated with the selected circuit cell models and definitions into said new circuit design.  
     
     
       14. The computer readable medium of  claim 13  wherein said step of synthesizing comprises: 
       optimizing the synthesis of said electronic circuit to best match a set of desired design parameter goals.